Some advice and gripes:
1: The UI. It's awful having all of the information you need in one single place as a list. There's a reason why bigger companies spread the information around the screen. The text is too small. Try enlarging it and adding a backdrop at least so that the ammo and waves and other stuff is more noticeable.
2: Running. You should give players the choice to run instead of doing so automatically. Or if you will run, don't use the stamina if it's the norm. It's not fun to have something taken away just because you're doing what any other person would so.
3: Stamina Bug. There's a bug where the stamina won't replenish once it reaches zero. I had it happen once and it is really frustrating.
4: Lack of content. The way you have it now is just like any other shooter. Move and shoot. Replenish ammo. Shoot again. There's nothing to keep one interested past the 3 or 4 wave mark. Maybe better enemy variety or new abilities the further in you get.
Now, I understand this is your first game, so I obviously don't expect you to make the next call of duty, but I do suggest on trying to figure out what you can do to make this more worthwhile to download. It will definitely help you with creativity and finding out what makes a game fun, as well as help you grow as a game developer. I hope to see improvement if you continue with this.